BURLINGTON — The Vermont Department of Public Health is encouraging residents to get an HIV test at their doctor’s office or at one of more than 30 free, anonymous testing sites around the state as part of National HIV Testing Day on Thursday.

The department said an estimated 100 people in the state have HIV but are not aware of it until they seek testing through their medical provider.

The department has a website, www.11years.org — that provides information about how the virus affects health, the importance of early diagnosis, and the range of services available to those who test positive for the virus. The department, along the Centers for Disease Control and Prevention, recommends that all sexually active people age 13 to 64 be tested for HIV.